Here's the thing: For some of us (like me) literally ALL of the people we text with have iPhones. You might find that hard to believe, but for me it's a reality. So I think the point is (again, for me) that "the need" for iMessage is that when the only people you text with ALL have iPhones, it doesn't matter that iMessage is not compatible with anything but iPhones. If you don't have an iPhone, YOU are the odd man out. YOU are the only one that doesn't have an iPhone. And when you're texting / sharing pictures / sharing videos with iPhone users, having iMessage is much better, easier and more convenient than NOT having iMessage.